Field of the Invention
The present invention relates to a deposition mask, and more particularly, to a deposition mask used in the manufacture of a display device.
Description of the Related Art
Electroluminescent elements, which are self-luminous display elements, are drawing attention as next-generation display elements due to their wide viewing angle, high contrast, and high response speed.
These electroluminescent elements are divided into inorganic electroluminescent elements and organic electroluminescent elements according to the material which forms a light-emitting layer. Organic electroluminescent elements have higher luminance and response speed than inorganic electroluminescent elements, and are capable of displaying color images. Due to these advantages, organic electroluminescent elements are being actively developed.
Display devices using organic electroluminescent elements are manufactured through various deposition processes, and a deposition mask is used in part of the manufacturing process. A deposition mask includes a mask frame and a mask sheet.
In the process of manufacturing a mask sheet, aperture portions may be formed by chemically etching a rolled metal plate. However, as the resolution of displays increases, apertures become smaller, and the gap between the apertures is reduced. Therefore, it is very difficult to manufacture a high-resolution mask using the chemical etching method.
To meet the demand for high-resolution displays, electroforming may be used in manufacturing a mask sheet. However, a mask sheet manufactured using electroforming is more deformed by heat than a conventional mask made of an Invar material. Therefore, the positions of apertures of the mask sheet may be changed by heat during a deposition process, and the deformation of the mask sheet due to heat may create deposition shadows, causing mask defects.